Magneto-optical recording device

ABSTRACT

A magneto-optical recording device has a flying head that floats over a magneto-optical disk according to the rotation of the magneto-optical disk. The flying head includes a head slider. A solid lubricant is applied to the bottom surface of the head slider facing the magneto-optical disk. Since the solid lubricant makes the flying head contact with the magneto-optical disk smoothly, the scratching and wear of the magneto-optical disk and the flying head decrease. Therefore, the reliability and the durability of the magneto-optical recording device can improve. Physical protrusions and recessions or holes containing fluorocarbon oil therein may be formed instead of the solid lubricant. In this case, the contact area between the flying head and the magneto-optical disk is also smaller than the case where physical protrusions and recessions are not formed. In addition, with a configuration such that thin-film layers made of a fluorocarbon resin having an excellent lubricity are formed on both sides of the bottom surface of the head slider, since the magneto-optical disk comes into contact with the head smoothly, the reliability and the durability of the magneto-optical recording device can improve.

FIELD OF THE INVENTION

The present invention relates to a magneto-optical recording devicethrough which information is recorded optically, more precisely to aflying head for magneto-optical recording.

BACKGROUND OF THE INVENTION

In recent years, the research and development of magneto-opticalrecording media as high density and large capacity memories has beenmuch carried out. In magneto-optical recording with magneto-opticalrecording media, a substrate that is made of glass, plastic, ceramicmaterials, etc. and is coated with a vertical magnetization filmcomposed of metal-magnetic substance, is used as a recording medium, andinformation is recorded on the recording medium by switching themagnetization direction of a desired portion on the verticalmagnetization film.

More concretely, when recording information, first, a recording mediumis initialized by applying the external magnetic field from an externalmagnetic field generation device to the recording medium. With thisoperation, the magnetization direction of the vertical magnetizationfilm on the recording medium is made uniform either upward or downward.

When the initialization is completed, a laser beam from light emittingmeans is irradiated on a desired recording portion of the recordingmedium. A temperature of the recording portion whereon the laser beam isirradiated rises, and when the temperature reaches or exceeds around theCurie point of the vertical magnetic film or its magnetic compensationpoint, the coercive force on the recording portion becomes zero orsubstantially zero. With this state, the magnetization direction isswitched by applying an external magnetic field (bias magnetic field)whose magnetization direction is opposite to the set direction of theabove-mentioned recording portion when initialized. The temperature ofthe recording portion decreases and eventually returns to the roomtemperature by stopping the irradiation of the laser beam on therecording portion. As described above, since the switched magnetizationdirection of the recording portion is kept, desired information can berecorded.

When reproducing information recorded in the above-mentioned way, alinearly polarized laser beam whose power is weaker than the one usedduring recording is irradiated on a recorded portion, and reflectedlight or transmitted light from the irradiated recording portion isdetected. The recorded information is reproduced by detecting therotation angle of the polarization plane of the reflected light ortransmitted light. More precisely, since the rotation angle ofpolarization plane varies depending on the magnetization direction ofthe recorded portion (magnetic Kerr effect of magnetic Faraday effect),information can be read out optically with the use of the magneticeffect.

Therefore, magneto-optical recording as rewritable large capacity memoryelement has been focused recently. For rewriting information recorded ona recording medium, the following requirements must be fulfilled.

(1) Initializing the recording medium.

(2) Improving an external magnetic field (bias magnetic field)generation device or a recording medium whereon information can berewritten without performing erasing operation.

To meet requirement (1), however, an initialization

device is separately demanded and two magneto-optical write heads may beneeded, thereby causing the number of parts to increase. That is to say,in case of erasing information with a single magneto-optical write head,the same time taken for recording is required for erasing. In the meantime, in order to meet requirement (2), the composition and thethickness of the magnetic film need to be controlled.

For the above reasons, the most effective means is the improvement of anexternal magnetic field (bias magnetic field) generation devicesatisfying requirement (2). Namely, information is recorded by, forexample, maintaining the output of a laser beam at a fixed level andswitching an external magnetic field at high speed. To switch theexternal magnetic field at high speed, a coil and a coil core forgenerating external magnetic field must be miniaturized to a greatdegree, and therefore, magnetic field generation areas become smaller.As a result, a magneto-optical write head and a recording medium mustcome close each other.

In order to get close the magneto-optical write head and the recordingmedium each other, a flying head in the shape of slider shown in FIG. 8has been known and adopted. The flying head comprises a head slidermeans 31 and a head coil means 32. As shown in FIG. 8, the head coilmeans 32 is formed at an edge of the head slider means 31. The bottomsurface of the head coil means 32 is aligned with the bottom surface ofthe head slider means 31. The head coil means 32 is connected to a powersource 37 that generates a magnetic field, and the direction of thegenerated magnetic field varies depending on the polarity of the powersource 37.

The head having the above configuration comes into contact with arecording medium at the time the recording medium starts rotating andstops rotating. Therefore, similar to computer hard disk cases wherelubricating oil such as fluorocarbon oil is applied to the disk surface,lubricating oil 33 may be applied to a protective resin film 34 (seeFIG. 8). With this application, the wear rate of the flying head and themagneto-optical recording medium can be reduced. Regarding the formationof the protective resin film 34, the protective resin film 34 is firstapplied to a vertical magnetization film 35 through the spin coating orother process and then hardened by an irradiation of ultraviolet light.The vertical magnetization film 35 is formed on a transparent substrate36.

The magneto-optical medium, however, is portable, and this point differsfrom the above-mentioned hard disk. Therefore, in case liquidlubricating oil is applied to the surface of the magneto-opticalrecording medium, it is difficult to keep the oil staying on thesurface, and therefore scratches may occur on the surface due to theabsence of the liquid lubricating oil. This causes the reliability ofthe magneto-optical recording medium to remarkably lower.

Additionally, some manufacturers produce magneto-optical recording mediawithout lubricating oil on their surface. In such a case, a problemarises, the magneto-optical recording media without lubricating oil arenot compatible with magneto-optical recording media produced by othermanufactures.

In the mean time, solid lubricating oil may be applied to a portion (thebottom surface of a head) of a flying head which comes into contact withthe surface of a magneto-optical recording medium. In this however solidlubricating oil to be applied to the flying head needs to havedurability of some hundreds times as high as that of solid lubricatingoil on the magneto-optical recording medium. Therefore, only applyinglubricating oil to the flying head was not sufficient for solving theabove problem.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a magneto-opticalrecording device having a flying head that can smoothly float over amagneto-optical recording medium when relative motion occurs between themagneto-optical recording medium and the flying head, and can givestable operation in a long term.

In order to achieve the above object, a magneto-optical recording devicerelating to the present invention comprises a lubricating member that ismounted on the bottom surfaces of a head slider means and a head coilmeans which come into contact with a magneto-optical recording medium,or at least on the bottom surface of the head slider means.

With the above configuration, since the flying head for magneto-opticalrecording smoothly makes contact with the magneto-optical recordingmedium, scratching and wear occur less on the magneto-optical recordingmedium and the flying head. As a result, the life of the flying head canbe prolonged, thereby permitting the reliability of the magneto-opticalrecording medium to increase. In addition, in this way, as themagneto-optical recording medium is compatible with magneto-opticalrecording media produced by other manufactures, a magneto-opticalrecording device suitable for various purposes can be provided. For theabove-mentioned lubricating member, for example, the head slider meansmay be coated with fluorocarbon resin. In this case, as well, since themagneto-optical recording medium does not make contact with the headslider means directly, the friction between the magneto-opticalrecording medium and the head slider means can be reduced.

A magneto-optical recording device relating to the present invention mayalso be configured such that physical protrusions and recessions areformed on the bottom surfaces of the head coil means and the head slidermeans which come into contact with the magneto-optical recording medium,or at least on the bottom surface of the head slider means. The bottomsurface may be coated with a fluorocarbon resin or the like, or physicalholes containing liquid lubricant such as fluorocarbon oil may be formedinstead of forming physical protrusions and recessions.

With the above configuration, the contact area between the flying headfor magneto-optical recording and the magneto-optical recording mediumbecomes smaller than the case where physical protrusions and recessionsor holes are not formed, thereby allowing the friction between them tobe reduced. Consequently, scratching and wear occur remarkably less onthe magneto-optical recording medium and the flying head.

For a fuller understanding of the nature and advantages of theinvention, reference should be made to the ensuring detailed descriptiontaken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 to FIG. 7 explain the present invention in detail.

FIG. 1 is an explanatory view of the first embodiment of the presentinvention illustrating a state in which a flying head formagneto-optical recording having a bottom surface to which a solidlubricant is applied floats over a magneto-optical disk.

FIG. 2 is an explanatory view of the third embodiment of the presentinvention illustrating a state in which a flying head formagneto-optical recording having the bottom surface on which physicalprotrusions and recessions are formed floats over a magneto-opticaldisk.

FIG. 3 is an explanatory view of the forth embodiment of the presentinvention illustrating a state in which a flying head formagneto-optical recording having the bottom surface on which afluorocarbon resin film is formed floats over a magneto-optical disk.

FIG. 4 is an explanatory view of the fifth embodiment of the presentinvention illustrating a state in which a flying head formagneto-optical recording having the bottom surface on which physicalholes containing liquid lubricant therein are formed floats over amagneto-optical disk.

FIG. 5 is an explanatory view illustrating a state in which a flyinghead for magneto-optical recording having the bottom surface on whichsolid lubricant applied physical protrusions and recessions are formedfloats over a magneto-optical disk.

FIG. 6 is an explanatory view illustrating a state in which a flyinghead for magneto-optical recording having the bottom surface providedwith a sintered body having physical protrusions and recessions, andholes containing liquid lubricant therein floats over a magneto-opticaldisk.

FIG. 7 is a perspective view illustrating the schematic configuration ofa flying head for magneto-optical recording used in the sixth embodimentof the present invention.

FIG. 8 is an explanatory view of a conventional example illustrating astate in which a flying head for magneto-optical recording floats over amagneto-optical disk having lubricating oil on the surface thereof.

DESCRIPTION OF THE EMBODIMENTS Embodiment 1

An explanation of the first embodiment of the present invention withreference to FIG. 1 yields the following.

As shown in FIG. 1, a magneto-optical disk as magneto-optical recordingmedium is composed mainly of a protective resin film 14, a recordingfilm 15 and a substrate 16.

The recording film 15 is formed on the substrate 16, and the protectiveresin film 14 is on the recording film 15 for the protection. Therecording film 15 has multilayer structure, for example a transparentdielectric film, a rare earth-transition metal alloy thin-film, and areflecting film (none of them is shown) are laminated. The protectiveresin film 14 protects the recording layer 15 from scratching, dust,oxidization, etc. Regarding materials for the protective resin film 14,for example an ultraviolet hardening resin that has the advantages ofeasy handling and saving processing time has been widely used. Theprotective resin film 14 is formed on the recording film 15 based on thespin coating or other process. More precisely, the ultraviolet hardeningresin is first applied to the recording film 15, and then ultravioletlight is irradiated on the ultraviolet hardening resin to harden it andto form the protective resin film 14.

As shown in FIG. 1, a flying head for magnetic recording is composed ofa head slider means 11 and a head coil means 12, and the head coil means12 is formed at an edge of the head slider means The flying head isconfigured such that the bottom surface of the head coil means 12 isaligned with the bottom surface of the head slider means 11.

The head slider means 11 is made of ferrite or ceramic materials, suchas Al₂ O₃ - TiC and CaTiO₃. For the coil core of the head coil means 12,MnZn ferrite or other material is used. A power source 17 whichgenerates a magnetic field is connected to the head coil means 12, andthe direction of a generated magnetic field varies depending on thepolarity of the power source 17. During the rotation of themagneto-optical disk, the head slider means 11 lets the flying head formagneto-optical recording float over the magneto-optical disk.

The flying head having the above configuration comes into contact with amagneto-optical disk when the magneto-optical disk starts and stopsrotating. A solid lubricant 13 (lubricating member) is applied to thebottom surfaces of the head slider means 11 and the head coil means 12.For the solid lubricant 13, for example, graphite (C), molybdenumsulfide (MoS₂), polytetrafluoroethylene (PTFE), monostearate,triacontyltrimethoxysilane, triacontanol or melamine-cyanurate is soloused or their mixtures are used.

A concrete method of forming the above solid lubricant 13 is describedbelow.

In case of using MoS₂, MoS₂ particles are dispersed in solvent and thebottom surfaces are then coated with the solvent by the spray coating,and the solvent is volatilized. For this type of spray, there is forexample "Rocol dry spray" of SUMICO Corp.

In case of using PTFE, PTFE particles whose diameters are not biggerthan 0.2 μm and an organic binder are mixed, and the mixed solution isapplied to and fixed on the bottom surfaces by the spray coating. Forthis type of spray, there is for example "Lubron LA" of DaikinIndustries, LTD.

In case of using triacontanol, it is dissolved in a solvent such asisopropyl alcohol and is applied to the bottom surfaces by the dipcoating, and the solvent is volatilized.

In case of using graphite, the sputtering process is carried out.Namely, the bottom surfaces is coated with a graphite thin-film based onthe sputtering process wherein Ar gas is directed into a vacuum vesselusing a carbon target.

When a magneto-optical disk is placed in the magneto-optical recordingdevice comprising the flying head for magneto-optical recording havingthe configuration described above, a laser beam from light emittingmeans (not shown) is irradiated on a desired recording portion of therecording film on the magneto-optical disk during the normal rotation ofthe magneto-optical disk. When the temperature of the desired recordingportion rises and reaches or exceeds around the Curie point or itsmagnetic compensation point, the coercive force on the recording portionbecomes zero or substantially zero. At that time, an external magneticfield (bias magnetic field) is applied to the recording portion so as toswitch the magnetization direction to a desired direction through thehead coil means 12. The magnetization direction can be switchedaccording to the polarity of the power source 17 of the head coil means12. When the irradiation of the laser beam on the above recordingportion is stopped, the temperature of the recording portion drops andeventually returns to the room temperature. Thus, as the magnetizationdirection of the recording portion which is switched inversely is kept,desired information can be recorded.

As described above, in the present embodiment, since the solid lubricant13 is applied to the bottom surfaces of the head slider means 11 and thehead coil means 12, the head slider means and the head coil means 12smoothly come into contact with the magneto-optical disk. As a result,scratching and wear occur less on the magneto-optical disk, the headslider means 11 and the head coil means 12, and a floating operation ofthe head can be carried out smoothly when the magneto-optical diskstarts rotating.

In the above embodiment, the solid lubricant 13 is applied to both thehead slider means 11 and the head coil means 12, however, it can beapplied only to the head slider means 11.

Embodiment 2

For the lubricating member of EMBODIMENT 1 described above, in order tobring about the above-mentioned effect, instead of the solid lubricant13, for example a fluorocarbon resin film can be formed at least on thebottom surface of a head slider means 11 that comes into contact with amagneto-optical disk. Needless to say, the fluorocarbon resin film canbe formed on both the bottom surfaces of the head slider means 11 and ahead coil means 12.

A case where the fluorocarbon resin film is formed on both the bottomsurfaces of the head slider means 11 and the head coil means 12, isdescribed in detail below. As to members whose functions are the same asthe members of EMBODIMENT 1, the same reference numbers are giventhereto and the detailed explanations are omitted here. For drawings, asthe configuration is the same as FIG. 1, the drawings are left out.

The preferable thickness for a fluorocarbon resin film 13 is 1 μm to 100μm, and the more preferable thickness is 10 μm to 20 μm. Thefluorocarbon resin film 13 is composed, for example, ofpolytetrafluoroethylene (hereinafter referred to as PTFE). Thefluorocarbon resin film 13 is formed as follows: the bottom surfaces ofthe head slider means 11 and the head coil means 12 are baked at atemperature of 400° C. for not less than two hours or thoroughlydegreased by cleaning with trifluoroethylene; the bottom surfaces arethen grounded (earth potential), a PTFE powder is negatively charged tobe applied to the bottom surfaces (the electrostatic powder coating);and the fluorocarbon resin film 13 is then formed on the bottom surfacesof the head slider means 11 and the head coil means 12 by baking thehead whose bottom surface is evenly coated with the PTFE powder at atemperature range of 360° C. to 380° C.

As described above, with the configuration such that the fluorocarbonresin film 13 is formed on the bottom surfaces of the head slider means11 and the head coil means 12, the head slider means 11 and the headcoil means 12 smoothly come into contact with the magneto-optical disk.As a result, scratching and wear occur less on the magneto-optical disk,the head slider means 11 and the head coil means 12, and a floatingoperation of the head can be carried out smoothly when themagneto-optical disk starts rotating.

Embodiment 3

The third embodiment of the present invention with reference to FIG. 2is described below.

As shown in FIG. 2, a magneto-optical disk as magneto-optical recordingmedium is composed mainly of a protective resin film 24, a recordingfilm 25 and a substrate 26.

The recording film 25 is formed on the substrate 26 and the protectiveresin film 24 is on the recording film 25 for the protection. Therecording film 25 has multilayer structure, for example a transparentdielectric film, a rare earth-transition metal alloy thin-film, and areflecting film (none of them is shown) are laminated. The protectiveresin film 24 protects the recording layer 25 from scratching, dust,oxidization, etc. Regarding materials for the protective resin film 24,for example an ultraviolet hardening resin like EMBODIMENT 1 is used.The protective resin film 24 is formed on the recording film 25 throughthe spin coating or other process in a similar way to EMBODIMENT 1.

As shown in FIG. 2, a flying head for magnetic recording is composed ofa head slider means 21 and a head coil means 22, and the head coil means22 is formed at an edge of the head slider means 21. The flying head isconfigured such that the bottom surface of the head coil means 22 isaligned with the bottom surface of the head slider means 21. LikeEMBODIMENT 1, the head slider means 21 is made of ferrite or ceramicmaterials. For the coil core of the head coil means 22, in the same wayas EMBODIMENT 1, MnZn ferrite or other material is used. A power source27 which generates a magnetic field is connected to the head coil means22, and the direction of a generated magnetic field varies depending onthe polarity of the power source 27. During the rotation of themagneto-optical disk, the head slider means 21 lets the flying head formagneto-optical recording float over the magneto-optical disk.

The flying head having the above configuration comes into contact with amagneto-optical disk when the magneto-optical disk starts and stopsrotating. On the bottom surfaces of the head slider means 21 and thehead coil means 22, physical protrusions and recessions 23 whose maximumheight R_(MAX) is 100 nm to 2500 nm are formed.

Table 1 shows the relation between the maximum height R_(MAX) of thephysical protrusions and recessions 23 and the coefficient of staticfriction μ_(s) between a magneto-optical disk and the head slider means21.

When the maximum height R_(MAX) is less than 100 nm, the coefficient ofstatic friction μ_(s) rises rapidly, while when the maximum height isnot less than 100 nm, the coefficient of static friction μ_(s) decreasesgradually as the maximum height R_(MAX) increases.

Generally, when the coefficient of static friction μ_(s) increases,scratching and wear tend to occur more on the magneto-optical disk, thusthe preferable maximum height R_(MAX) is at least 100 nm. On thecontrary, if the maximum height R_(MAX) is not less than 2500 nm,floating height becomes too small. Therefore, the preferable maximumheight R_(MAX) for the physical protrusions and recessions 23 is 100 nmto 2500 nm.

                  TABLE 1                                                         ______________________________________                                                         COEFFICIENT OF                                               MAXIMUM HEIGHT R.sub.MAX                                                                       STATIC FRICTION μ.sub.s                                   ______________________________________                                         50 nm           1.60                                                          100 nm          0.43                                                         2500 nm          0.37                                                         ______________________________________                                    

The physical protrusions and recessions 23 are formed in the followingway.

First, the bottom surfaces of the head slider means 21 and the head coilmeans 22 are burnished with a lapping paper with diamond abrasive grainshaving a fineness of not less than #4000 mesh.

Then the surfaces are burnished with a lapping paper using less finerdiamond abrasive grains having a fineness of, for example, not less than#400 to #4000 mesh, so that physical protrusions and recessions 23 of apreferable maximum height R_(MAX) are formed. The physical protrusionsand recessions 23 can be formed in any shape.

When a magneto-optical disk is placed in a magneto-optical recordingdevice comprising a flying head of the above configuration, a laser beamfrom light emitting means (not shown}is irradiated on a desiredrecording portion of the recording film 25 on the magneto-optical disk.When the temperature of the recording portion reaches or exceeds aroundthe Curie point or its magnetic compensation point, the coercive forceon the recording portion becomes zero or substantially zero. At thistime, an external magnetic field (bias magnetic field) is applied to therecording portion through the head coil means 22 to switch themagnetization direction into a desired direction. The magnetizationdirection can be switched according to the polarity of the power source27 of the head coil means 22. When the irradiation of the laser beam onthe recording portion is stopped, the temperature of the recordingportion falls and eventually returns to the room temperature. Thus,desired information is recorded by keeping the switched magnetizationdirection of the recording portion.

As described above, in the present embodiment, the physical protrusionsand recessions 23 whose maximum height R_(MAX) is 100 nm to 2500 nm areformed on the bottom surfaces of the head slider means 21 and the headcoil means 22. As a result, the contact area between the head slidermeans - head coil means 22 and the magneto-optical disk becomes smaller,and the friction between them can be reduced. Therefore, scratching andwear occur less on the head slider means 21 and the head coil means 22,and a floating operation of the head can be carried out smoothly at thetime the magneto-optical disk starts rotating.

The contact area does not mean an apparent contact area but a truecontact area. With a true contact area A and the shear strength of atrue contact area σ, a frictional force F is as follows: F=σ·A.Therefore, if the shear strength is constant, friction force decreasesas the true contact area becomes smaller, i.e., the head slider means 21and the head coil means 22 smoothly come into contact with themagneto-optical disk.

In the above embodiment, the physical protrusions and recessions 23 areformed on both the head slider means 21 and the head coil means 22,however, they may be formed only on the head slider means 21

Embodiment 4

The fourth embodiment of the present invention with reference to FIG. 3will be described below.

In order to bring about the above-mentioned effect, instead of thephysical protrusions and recessions 23 of EMBODIMENT 3, for examplefluorocarbon resin film can be formed at least on the bottom surface ofa head slider means 21 that comes into contact with a magneto-opticaldisk. Needless to say, the above fluorocarbon resin film can be formedon both the bottom surfaces of the head slider means 21 and a head coilmeans 22.

In this embodiment, the fluorocarbon resin film is formed on both thebottom surfaces of the head slider means 21 and the head coil means 22,and the detailed description with reference to FIG. 3 is stated below.As to members whose functions are the same as the members of the aboveembodiments, the same reference numbers are given thereto and thedetailed explanations are omitted here.

The preferable thickness of a fluorocarbon resin film 23 is 1 μm to 100μm, and the more preferable thickness is 10 μm to 20 μm. Thefluorocarbon resin film 23 is composed, for example, oftetrafluoroethylene-ethylene copolymer. The fluorocarbon resin film 23is formed as follows: a silane coupling agent 28 is first applied to thebottom surfaces of the head slider means 21 and the head coil means 22and then the bottom surfaces are coated with thetetrafluoroethylene-ethylene copolymer by the fluidization dip coating;and the head whose bottom surface is evenly coated with the copolymer isthen baked at a temperature range of 290° C. to 340° C. to form thefluorocarbon resin film 23 on the bottom surfaces of the head slidermeans 21 and the head coil means 22. For the formation of fluorocarbonresin film 23, materials are not restricted to the ones used inEMBODIMENT 2 and this embodiment, and for example, powder oftetrafluoroethylenehexafluoropropylene copolymer (FEP),polytrifluorochloroethylene (PTFCE) and polyvinylidene fluoride (PVdF)can be applied to the head and then baked.

With the above configuration such that the fluorocarbon resin film 23 isformed on the bottom surfaces of the head slider means 21 and the headcoil means 22, the head slider means 21 and the head coil means 22 comeinto contact with the magneto-optical disk smoothly. Consequently,scratching and wear occur less on the head slider means 21 and the hardcoil means 22, and a floating operation of the head can be carried outsmoothly at the time the magneto-optical disk starts rotating.

Table 2 below shows coefficients of static friction (μs), measuredinitial values of coefficients of dynamic friction (μ_(f)) and valuesmeasured after 10000 contact start/stop (CSS) with respect to therespective heads (1) to (3). In the table, (1) is the head slider ofEMBODIMENT 1, (2) is the head slider of EMBODIMENT 4, and (3) is theordinal head slider. Additionally, the symbols μ_(s) and μ_(f) show thecoefficients of static friction and the dynamic friction coefficients,respectively, between an ultraviolet hardening resin overcoatedmagneto-optical disk and the respective sliders of (1) to (3). Thevalues after 10000 CSS was measured after 10000 abrasion tests, in whichthe head slider means floated over the magneto-optical disk or came intocontact with it as the magneto-optical disk started rotating or stoppedrotating.

As is clear from FIG. 2, the initial value of the ordinal head slider of(3)is μ_(s) >1.0, while the values after 10000 CSS of the head sliders(1) and (2) are still μ_(s) <1.0. This means that the floatingoperations of the head at the time of the magneto-optical disk startsrotating can be carried out smoothly even after 10000 CSS. When thevalue becomes μ_(s) >1.0, abnormalities occur in a suspension forsupporting the head slider.

                  TABLE 2                                                         ______________________________________                                        INITIAL VALUE    VALUE AFTER 10000 CSS                                              μ.sub.s                                                                             μ.sub.f                                                                              μ.sub.s                                                                             μ.sub.f                                  ______________________________________                                        (1)   0.35     0.26      0.36     0.25                                        (2)   0.38     0.28      0.43     0.30                                        (3)   1.60     1.25      --       --                                          ______________________________________                                    

The values shown in Table 2 were obtained under the followingmeasurement condition: depressing force of the suspension was 5 gf, andthe magneto-optical disk rotated at a rotation speed of 2 rpm (rotationper minute) when μ_(s) and μ_(f) were measured.

Embodiment 5

The fifth embodiment of the present invention with reference to FIG. 5will be described below.

As shown in FIG. 4, a magneto-optical disk as magneto-optical recordingmedium is composed mainly of a protective resin film 44, a recordingfilm 45 and a substrate 46.

The recording film 45 is formed on the substrate 46, and the protectiveresin film 44 is on the recording film 45 for the protection. Therecording film 45 has multilayer structure, for example a transparentdielectric film, a rare earth-transition metal alloy thin-film, and areflecting film (none of them is shown) are laminated. The protectiveresin film 44 protects the recording layer 45 from scratching, dust,oxidization, etc. Regarding materials (or the protective resin film 44,similar to EMBODIMENT 1, an ultraviolet hardening resin is used. Theprotective resin film 44 is formed on the recording film 45 through thespin coating or other process in the same manner as EMBODIMENT 1.

As shown in FIG. 4, a flying head for magnetic recording is composed ofa head slider means 41 and a head coil means 42, and the head coil isformed at an edge of the head slider means 41. The flying head isconfigured such that the bottom surface of the head coil means 42 isaligned with the bottom surface of the head slider means 41. The headslider means 41 is made of ceramic materials, such as SiC sintered bodyand Al₂ O₃ -TiC mixed sintered body. For the coil core of the head coilmeans 42, similar to EMBODIMENT 1, MnZn ferrite or other material isused. A power source 47 which generates a magnetic field is connected tothe head coil means 42, and the direction of a generated magnetic fieldvaries depending on the polarity of the power source 47. The head slidermeans 41 lets the flying head for magneto-optical recording float overthe magneto-optical disk.

The flying head of the above configuration comes into contact with themagneto-optical disk when the magneto-optical disk starts and stopsrotating. The bottom surface of the head slider means 41 is providedwith physical holes 43 having a depth of 10 nm to 2500 nm, andfluorocarbon oil such as perfluoropolyether is contained in the holes.

One example of manufacturing method of the head slider means 41 isdescribed below.

First, SiC fine powder whose diameter is substantially 0.5 μm and asintering agent such as B, C, B₄ C and Al₂ O₃ are mixed and hardenedinto a predetermined shape by pressing, and then it is heated to 2000°C. to 2200° C. at atmospheric pressure and is sintered. Next, the bottomsurface of the head slider means 41 is burnished with diamond grindingstones. The holes 43 having a depth of substantially 250 nm are formedthrough this process, and the fluorocarbon oil is applied to the bottomsurfaces and is contained in the holes 43.

When a magneto-optical disk is placed in a magneto-optical recordingdevice having a flying head of the above configuration, a laser beamfrom light emitting means (not shown) is irradiated on a desiredrecording portion of the recording film 45 on the magneto-optical disk.When the temperature of the desired recording portion rises and reachesor exceeds around the Curie point or its magnetic compensation point,the coercive force on the recording portion becomes zero orsubstantially zero. At that time, an external magnetic field (biasmagnetic field) is applied to the recording portion through the headcoil means 42 to switch the magnetization direction into a desireddirection. The magnetization direction can be switched according to thepolarity of the power source 47 of the head coil means 42. When theirradiation of the laser beam on the recording portion is stopped, thetemperature of the recording portion drops and eventually returns to theroom temperature. Thus, desired information is recorded as the switchedmagnetization direction of the recording portion is kept.

As described above, in the present embodiment, the holes 43 are formedon the bottom surfaces of the head slider means 41, and the fluorocarbonoil (liquid lubricant) is applied to the bottom surfaces and iscontained inside the holes. With the configuration, the fluorocarbon oilcontained in the holes 43 oozes out onto the bottom surface of the headslider means 41 when the magneto-optical disk rotates. Since the oozedoil functions as lubricant, it is difficult for the head slider means 41to come into contact with the magneto-optical disk directly, therebyallowing the friction between the head slider means 41 and themagneto-optical disk to be more reduced than the cases of EMBODIMENT 1and EMBODIMENT 3. As s result, scratching and wear of themagneto-optical disk, the head slider means 41 and the head coil means42 extremely decrease. The fluorocarbon oil oozes into the holes 43again when the magneto-optical disk stops rotating. Consequently, evenwhen a liquid lubricant such as fluorocarbon oil is used, long-timelubricating effects can be expected similar to the case where solidlubricant is used.

When the depth of the holes 43 is not more than 10 nm, it is difficultfor a liquid lubricant such as fluorocarbon oil to ooze into the holes,while when the depth is not less than 2500 nm, it is difficult for theliquid lubricant to ooze out onto the surface. Therefore, the preferabledepth for the holes 43 is 10 nm to 2500 nm.

In this embodiment, a case where the physical holes 43 are formed onlyon the head slider means 41 and the fluorocarbon oil is contained in theholes 43, is explained, however, the holes 43 containing thefluorocarbon oil can be formed on both the head slider means 41 and thehead coil means 42. In addition, oil such as fluorosilicon oil, siliconoil, and olefin oil can be used instead of fluorocarbon oil to obtainthe above effects.

In the above embodiments, a flying head to which solid lubricant isapplied (FIG. 1), a flying head whereon physical protrusions andrecessions 23 are formed (FIG. 2), a flying head whereon a fluorocarbonresin film is formed (FIG. 3) and a flying head whose bottom surface isprovided with holes to which liquid lubricant is applied and the liquidlubricant is contained in the holes (FIG. 4) were described. In order toobtain a better lubricity due to the synergistic effect, the followingtwo heads can be employed: a flying head having a bottom surface 53 onwhich physical protrusions and recessions are formed and solid lubricantis applied thereto (FIG. 5); and a flying head having a bottom surface63 provided with physical protrusions and recessions on theabove-mentioned sintered body comprising holes, liquid lubricant that iscontained in the holes (FIG. 6). Regarding members of FIG. 5 and FIG. 6which have the same functions as the members of FIG. 1 and FIG. 4, forconvenience' sake, the same reference numbers are given to them and thedetailed explanations are omitted here.

Embodiment 6

The sixth embodiment of the present invention with reference to FIG. 7will be explained below.

FIG. 7 is a perspective view illustrating the schematic configuration ofa flying head for magneto-optical recording employed in amagneto-optical recording device of this embodiment.

The flying head of the present invention is composed mainly of a headslider means 1 receiving a floating force and a head coil means 2 aroundwhich a lead wire 3 is wound. Thin-film layers 4 made, for example, of afluorocarbon resin film of a thickness of 5 μm are symmetrically formedon the both right and left sides of the bottom surface of the headslider means 1 with respect to the rotating direction of amagneto-optical disk. Consequently, a gutter 5 whose depth equals thethickness of the thin-film layer 4 is formed in the middle of the bottomsurface where the thin-film layer 4 is not formed. The gutter 5 ofshallow depth can be made easily on the bottom surface of the headslider means 1 by reducing the thickness of the thin-film layer 4.

An example of the procedure for forming the thin-film layer 4 is asfollows. First, an area of the bottom surface of the head slider means 1which is expected to be the gutter 5 is masked, and liquid fluorocarbonresin is applied to the entire bottom surface by the spray coating orthe dip coating, and then the liquid fluorocarbon resin is hardened byirradiating ultraviolet light, heating, drying or other method. Materialfor forming the thin-film layer 4 is not restricted to fluorocarbonresin, any resin which has an excellent lubricity can be used. If thecoefficient of the static friction between a resin and a magneto-opticaldisk surface is 1 or less, it is judged that the resin has goodlubricity. Even resin whose lubricity is not so good can be used byapplying lubricant such as perfluoropolyether to the formed thin-filmlayer 4 so as to improve its lubricity.

Additionally, SiO₂ or inorganic materials such as carbon may be used fora thin-film layer 4. In case of forming the thin-film layer of SiO₂,masking is performed in the above-described manner, and then alcoholsolution of tetrahydroxysilane is applied to the entire bottom surface,dried and baked.

In case of forming a thin-film layer 4 of carbon, after masking, acarbon film is formed through the sputtering process, the evaporationprocess, the CVD (Chemical Vapour Deposition) process or other process.In case of using these inorganic materials, it is preferable to applylubricant to the thin-film layer 4 in order to improve its lubricity.

In a magneto-optical disk device comprising the above-mentioned flyinghead for magneto-optical recording, when a magneto-optical disk rotatesat a high speed, the flying head for magneto-optical recording floatsover the magneto-optical disk due to a floating force exerted upward onthe head by air flowing between the head slider means I and themagneto-optical disk. When the floating height reaches substantially 5μm, the floating force is balanced with the depressing force exerteddownward on the head by a suspension (not shown) for supporting the headslider means 1. At this time, the floating force is distributed intotwo, right side and left side by the gutter 5, thereby permitting toobtain a stable floating condition.

During recording information, a laser beam of a fixed light amount isirradiated on the magneto-optical disk and rises the temperature of amagnetic film to reach or exceed around the Curie point or its magneticcompensation point to make the coercive force of the recording portionwhereto the laser beam is applied zero or substantially zero, and then amagnetic field setting current that is switched at a high speedaccording to recording signals is applied to the lead wire 3 of the headcoil means 2, so that high-speed switched magnetic field can be appliedeffectively to the recording portion and data can thus be recorded at ahigh speed by overwriting.

In EMBODIMENT 1 to EMBODIMENT 6 described above, a flying head formagneto-optical recording which is mounted on a magneto-opticalrecording device is explained, however, the present invention can beadopted for the flying heads employed in other magneto-optical recordingdevices or other devices in which compatible disks are used.

As aforesaid, a magneto-optical recording device relating to the presentinvention is configured such that a lubricating member is formed on thebottom surfaces of a head coil means and a head slider means, which makecontact with a magneto-optical recording medium, or at least on thebottom surface of the head slider means. According to the configuration,a flying head for magneto-optical recording smoothly comes into contactwith the magneto-optical recording medium, so that the scratching andwear of the magneto-optical recording medium and the flying head formagneto-optical recording decrease. As a result, the life of the flyinghead for magneto-optical recording can be prolonged, causing thereliability of the magneto-optical recording device to increase. Inaddition, the present invention is compatible with magneto-opticalrecording media produced by other manufactures, so that amagneto-optical recording device suitable for various purposes can beoffered.

Moreover, a magneto-optical recording device comprising a flying headfor magneto-optical recording of the present invention may be configuredsuch that physical protrusions and recessions or holes containing liquidlubricant therein are formed on the bottom surfaces of the head coilmeans and the head slider means of the flying head which come intocontact with a magneto-optical recording medium, or at least on thebottom surface of the head slider means. In this case, as well, sincethe contact area between the flying head for magneto-optical recordingand the magneto-optical recording medium becomes smaller than the casewhere the physical protrusions and recessions or holes are not formed,the friction between them can be diminished. As a result, the scratchingand wear of the magneto-optical recording medium and the flying head canbe further reduced.

The invention being thus described, it will be obvious that the same maybe varied in many ways. Such variations are not to be regarded as adeparture from the scope of the invention.

There are described above novel features which the skilled man willappreciate give rise to advantages. These are each independent aspectsof the invention to be covered by the present application, irrespectiveof whether or not they are included within the scope of the followingclaims.

What is claimed is:
 1. A magneto-optical recording device comprising aflying head for magneto-optical recording which floats over amagneto-optical recording medium according to the rotation of themagneto-optical recording medium, the flying head having:a head slidermeans for making the head float over the magneto-optical recordingmedium, the head slider means having a first bottom surface which comesinto contact with the magneto-optical recording medium; and a head coilmeans for generating an external magnetic field for recordinginformation on the magneto-optical recording medium, the head coil meanshaving a second bottom surface which comes into contact with themagneto-optical recording medium, wherein said first bottom surfacecomprises physical holes having a depth of between 10 nm to 2500 nm andcontaining a liquid lubricant therein.
 2. A magneto-optical recordingdevice comprising a flying head for magneto-optical recording whichfloats over a magneto-optical recording medium according to the rotationof the magneto-optical recording medium, the flying head having:a headslider means for making the head float over the magneto-opticalrecording medium, the head slider means having a first bottom surfacewhich comes into contact with the magneto-optical recording medium; anda head coil means for generating an external magnetic field forrecording information on the magneto-optical recording medium, the headcoil means having a second bottom surface which comes into contact withthe magneto-optical recording medium, wherein said first bottom surfacecomprises physical protrusions and recessions the maximum height ofthese physical protrusions and recessions being in the range of 100 nmto 2500 nm, and these physical protrusion and recessions including holeshaving a depth of 10 nm to 2500 n, the holes containing a liquidlubricant therein.
 3. A magneto-optical recording device as defined inclaim 1 or claim 2, wherein the liquid lubricant is fluorocarbon oil,fluorosilicon oil, silicon oil or olefin oil.
 4. A magneto-opticalrecording device comprising a flying head for magneto-optical recordingwhich floats over a magneto-optical recording medium according to therotation of the magneto-optical recording medium, the flying headhaving:head slider means for making the head float over themagneto-optical recording medium, the head slider means having a firstbottom surface which comes into contact with the magneto-opticalrecording medium; and a head coil means for generating an externalmagnetic field for recording information on the magneto-opticalrecording medium, the head coil means having a second bottom surfacewhich comes into contact with the magneto-optical recording medium,wherein said first bottom surface has right and left sides along therotating direction of the magneto-optical recording medium and saidright and left sides each comprising a laminated thin-film layer made offluorocarbon resin, SiO₂ or carbon.